Blending collagen, methylcellulose, and whey protein in films as a greener alternative for food packaging: Physicochemical and biodegradable properties

Alternative materials to replace the synthetic plastics are being developed using agro-based sources, but despite their promising results, these materials still need to have their performance improved to be used in packaging. Blending different molecules can combine the properties of each polymer resulting in the overall performance improvement of the material. In the present study, collagen, whey protein, and methylcellulose were investigated in the development of individual films and blends. They were produced by the casting technique and evaluated for their packaging-related characteristics (including mechanical, barrier, and color properties), microstructure, thermal properties, and biodegradability in soil. Methylcellulose films presented excellent technological properties, such as total solubility in water, high tensile strength (15.78 MPa), transparency (30.4%), and good barrier to water vapor (0.43 g·mm/h·m²·kPa). In the blends with collagen and whey protein, it was responsible by the increase in tensile strength, barrier, and thermal properties. Collagen films presented the highest elongation at break (101.4%), while whey protein films showed lower solubility in water (28.3%). All the samples tested were completely biodegraded in 10 days in soil. Potential applications for the materials developed include soluble sachets for powdered foods due to the high solubility of some samples, as well as oil containers and capsules for instant coffee machines.